Inconceivable!
by Forever-Furuba
Summary: Merlin takes an absurd amount of time to realize Jim is a Changeling, assuming instead that the Trollhunter is just really sarcastic and oddly devoted to a running joke with his trainer. The Amulet of Daylight couldn't possibly have chosen an actual Changeling as its Champion … right? Canon divergent but still has lots of spoilers for Season 3!


**This is not canon for my other Changeling!Jim fic, _Becoming The Mask_ , which will diverge quite sharply before reaching Season Three; but it does use the same backdrop of "Toby, Darci, Mary, and Claire all find out about trolls at the same time" and "Jim always knew he was a Changeling and changed sides to protect his loved ones" and "Blinky and AAARRRGGHH know Jim's secret" – although by this point in the timeline, it's not a secret anymore.**

* * *

In retrospect, there had been signs.

"I thought you'd be taller. Yes, much taller … and older. How old are you? Ten?"

"Four hundred and thirty. Rough estimate."

The boy said it perfectly flatly, but it had to be a joke. Everyone knew humans didn't live that long. Perhaps the bland delivery was the fashion for joke telling in this modern era.

* * *

"The real battle is over this way."

"So you're taking us out of the illusion, then?" the young Trollhunter sneered. "Trolls died in this fight. Show some respect."

Merlin dismissed that. "While you were focused on the battle," he told the talkative one with extra eyes and arms, "there were events unfolding that you were unaware of."

"I suppose fighting for our lives would be a _little_ distracting." Ah, so that was where the boy got it.

The boy gasped when they got close enough to see the duel of sorcery. One of his knees bent as though he were about to kneel.

"The Eldritch Queen," he whispered.

"Yes. The Pale Lady, Morgana, Mother of Monsters."

"None of our history books speak of this," said his trainer.

"Well, books don't talk for one thing. This was the true Battle of Killahead." The Trollhunter broke off staring at Morgana to glare briefly at Merlin. "Morgana is as ancient as I, or perhaps even more so. Craving chaos, she sowed dissension between humans and trolls."

"Hence the Changelings." The Trollhunter gestured to himself. "We thought she originally meant it diplomatically, but … turning trolls into humans and vice-versa would _force_ confrontation. Even before Gumm-Gumms got the idea of Changeling spies."

"Vice-versa?" the trainer asked.

"In theory. I don't know if she ever did it."

"Hence the Eternal Night," Merlin corrected him. The Changelings had been a side-project at best. "If trolls could not survive in daylight, what if the night were everlasting? The only way to stop her was to expend almost all of my power, and confine her for as long as possible."

* * *

"Well, that was a super-fun thing I never want to do again." The boy stretched and flexed in his restored armour. "How did you know the sword could split a flood like that? I feel like the Ghost Trollhunters would've bragged if there was a precedent."

"You can do more than you realize … and you will, when you help me destroy Morgana."

Merlin's Champion froze up. "I … don't know if I can do that. It was hard enough turning on Gunmar. I don't know if I can betray _her_ , too."

"Nonsense!" The four-armed troll clapped three of them on the Trollhunter's upper back. "You commit treason every time you don that armour."

"Why do you think I hardly ever say the full incantation?"

Merlin figured it out. Of course, since his Amulet had only ever picked trolls before, the trolls must have accused the _human_ Trollhunter of being a Changeling when it selected him. As if Merlin's creation would select one of Morgana's abominations! A gaggletack would quickly disprove that nonsense, but the idea must have survived as a running joke between the Trollhunter and his trainer.

* * *

"Merlin the Immortal! What an honour. Allow me to introduce myself. Waltolomew Stricklander; Walt Strickler for short. I've been mentoring the Trollhunter –"

"Spare me the life story." He could sense Morgana's magic on this one, hovering over him like a stench. "Now and forever … Changeling."

The mood in the room became inexplicably tense. Several of the watching humans flinched. "At least he didn't say the other word," the fat one muttered.

"That's it; you've lost Chef Jim privileges." The Trollhunter snatched the plate out of Merlin's hands and replaced it with a box. "You can eat cereal. It's mostly grain, some dried fruit. You can have real food when you're ready to be polite."

* * *

"Time is of the essence. Take me to the nearest blacksmith at once."

"What are you making, exactly?" The Trollhunter's team made no move to get up from their various chairs.

"It's none of your concern now."

"It is if you want our help. Never agree to anything before knowing all the terms, especially when magic is involved."

"… It's a potion that will help protect your town when Morgana escapes."

"See? Now we've affirmed we have a common goal, which makes us want to help you." Merlin did not care for the Trollhunter's condescending tone. "So, if you want a blacksmith, we're going to have to look up the nearest Renaissance Fair, or maybe one of those 'live history' villages. It's not a common skill anymore because of advances in machinery, so there's not a forge in every town. The only forge in Arcadia is the Hero's Forge down in Trollmarket, and that's more of a metaphor."

"Checking." The girl with longer dark hair was looking at one of those odd rectangles humans nowadays seemed to carry with them. "Yeesh, that's gonna be a long drive. And they're probably not gonna just let you walk in and use it, so we might have to break in after hours."

* * *

"To free Morgana, the staff must be wielded by the hand of a human who can speak the trollish incantation."

"You're kidding," said the Trollhunter. "Human hands, trollish tongue? That's literally _any_ Changeling. Okay, so our fluency and literacy rates in trollish aren't great, but for our Lady, we'd learn. And even if Changelings in human form don't 'count' as human for this spell, we're spoiled for choice." He gestured at his friends. "Blinky's been teaching the four of them for ages now, and Mom wanted lessons once she found out too."

* * *

"These ingredients hold greater purpose. To turn you into a troll."

The Trollhunter had looked indignant, defensive, and sulky by turns throughout the conversation, but now his face became absolutely blank.

"You're going to undo me being a Changeling?"

"This is not the time for jokes." Merlin was familiar with the concept of using humour to ease or deflect pain, and he could sympathize – as well as he was able to feel sympathy – with the boy needing that outlet when the fate of the world rested on his shoulders, but really, that gag had gone on long enough –

"Who's joking?" Now the boy seemed puzzled and annoyed. "If you change me back into a normal troll, I lose my sunlight immunity, and that's played to my advantage too many times for me to willingly give it up."

Merlin let out a frustrated noise.

"In my rest, I saw a way to finally end the stalemate between Morgana and myself. I need a champion with a foot in both worlds. The elixir will reform you, into a half-troll. You were chosen by the Amulet as the first human Trollhunter, but you were never destined to remain so. To protect the world you love, to be champion for both humanity and trollkind, you must become both _troll_ and _hunter_."

He did not expect the boy to laugh. He was forced to consider that his Amulet may have chosen a madman.

"The Amulet really does have a mind of its own, doesn't it? It cut right to the chase and now we can skip a step. _I'm already both_."

With Morgana's hand infused into the Amulet, every Trollhunter felt a little bit like her, magically speaking. For the first time since they met, the wizard reached under that to sense the boy's personal aura.

Merlin sat down heavily. "You're a _Changeling_?!"

"You're _just_ realizing this _now_?! I've literally called myself a Changeling, in front of you, repeatedly."

In retrospect, there had been signs.

* * *

 **This is intended as a little parody piece about Merlin's refusal to see the obvious when it clashes with his established worldview. It will not be expanded.**

 **It was an interesting experience to write from Merlin's perspective. Fun thing to notice when rereading: he never thinks of anyone other than himself of Morgana by name. I didn't realize I'd written him like that until I got to the end (which I had written first and where he does refer to Jim by name in my rough draft) and it jarred with the earlier segments. I also debated whether to have 'there had been signs' as the start or the end of the story and finally decided it had a neat 'looping' effect if written in both. Like, after Merlin finally has this obvious fact sledgehammered into his skull, he has a flashback of all the _really obvious signs_ that he previously ignored.**

Edit, as of 2019/07/21: **It occurred to me there appears to be a plothole in this fic. Namely, why would Jim be in human form if Merlin's tomb is warded against outside magic?**

 **To that, I point out Toby's warhammer.**

 **The hammer collapses into its 'fun-size' when the characters pass the ward's boundary. However, being collapsible was an enchantment that Blinky put on the hammer. If the hammer were truly reverting to its unenchanted state, it would be stuck at full size with no gravity hex. Instead, it shrinks down to its most harmless state.**

 **Likewise, Jim was either in human form when he entered the cave and got stuck like that, or the ward for some reason pushed him from troll form to human form. I think the first option makes more sense.**


End file.
